2 Questions: small rocket stove heating and cooking

Hi I have 2 questions

I'm moving into a small two person caravan and i would like to put in rocket stove large enough to heat and cook.
I would like to know two things, if any one could help i would be incredibly grateful.

1) what is the minimum hight of the heat riser i could use on a 4 in system, bearing in mind that there wouldn't be much of a horizontal run, the chimney would maybe run five feet horizontally then outside and up.

2) My second question is maybe a little more complex. because i intend to be living in the caravan winter and summer and will want to cook without the radiant heat, i would like to know if could do two things with the rocket stove? 1: put a hole in the top of the barrel with a heavyduty close removable section, much like an aga/rayburn i use at the moment (see the right hand side of this stoves cook plate: http://mud4fun.files.wordpress.com/2012/09/new_rayburn-1.jpg). My concern is that i might not get a tight enough fit and that there would be a leaking of gasses from the top of the barrel. 2: if not i would like to know if i could create an easily removable barrel so i could switch from rocket mass heater to a conventional rocket stove quickly and efficiently, so i could use the stove either for direct heat cooking or radiant heat.

If anyone could give me an answer or let me know if im barking up the wrong tree and would be better off having both a rocket stove and a rocket stove heating unit please let me know I would really appreciate it asap as time is of the essence and i don't want to embark on a fruitless endeavour.

Thanks

Louis

Louis : There is no-one who can give you a good answer to your questions, because of the unknown variables ! First we need to have a clear understanding of what you mean by
a 4'' Rocket Stove, and we need a great deal of information about where you are planning of placing it ! Fortunately we have a little time to play with, if you are truly serious about
moving forward on this project !

A brief history, Rocket Stoves came 1st, and were intended to be very efficient replacements for the traditional 3-rock fires that 40% of the Worlds people still use for cooking,
Rocket Stoves areNot usually hooked up to an outside chimney, and as such are not meant for use indoors ! For cooking they are "rocket'' fast - tho they ned a skilled hand to be
used near efficiently ! Do you have much experience living with wood heat/cooking ? In this case No is a good answer as you will have less to un-learn !

The Pocket Rocket is meant for heating only, and a 4'' model will melt blacktop, setting it on fire, with no more than a stretched canvas for a wind break, they are often used by
icefishermen, when properly installed indoors, and ducted outside the pocket rocket pumps most of it's heat outdoors, it truly is a very intense way to heat a small area and you
will notice the cold air drafts created by this units need for 'make-up air' !

The Rocket Mass Heater R.M.H. Has been built in units as small as 4'' with probably 1 in a 100 providing service thru at least 1 heating season before being torn out and replaced
with something Else. There are many reasons for this, 4'' is a sub-optimal unit that I personally have never tried, It should only be attempted by an experienced R.M.H. builder,
and then only after living with a larger unit for at least 1 heating season to learn how your R.M.H. works !

The Secret behind the great efficiencies of R.M.H.s is the Thermal Mass, which will weigh in at over 1 ton, and most be located in the center of your Caravan over the axle, and
centered from left to right for weight distribution ! It is the Use of this Thermal mass, that absorbs heat from the hot exhaust gas stream, Re-radiating it out slowly into your
Caravan! Any adaptation that attempts to decrease this mass is doomed to increase the amount of heat that is vented out through your chimney !

TheRocket Stove works very well with small pieces of well split, VERY DRY wood ! You need to have storage for all of that wood, a whole seasons worth, undercover and close to
hand! This, and the additional weight load on your Caravans suspension limits the Tour-ability of your Caravan !

If you were not planing on using your Caravan for travel, this opens many opportunities to re-locate your heating and cooking to an attached area tied to your caravan !

Please write back and share a little more information to let us see how we can help you make your future plans doable !

For the Good of the Craft ! Think like Fire! Flow like Gas, Don't be the Marshmallow! As always, all comments and questions are solicited and Welcome ! Big AL

Thank you for your reply i really appreciate the information,

What i ment by a 4 in system was that i would be using 4in stove pip for J tube and the flue. the reason i thought 4in was only because it only needs to be a small system. So jumping up to a six inch if its generally considered to be a safer bet would be no trouble.

The caravan will be static so I probably be doing something with thermal mass, I think i have a good understanding with regards to the principles of a RMH, and Rocket stoves and I was wondering if the two could be combined but Im beginning to think that perhaps the combination of the two might not be the best idea.

However, one question I really would like to know the answer to is what is the minimum hight for the heat riser on a six in system (that is, a heat riser made of six in stove pip). the reason being is that i have a two barrels one about 2ft tall the other 3ft and i was planning on using the smaller as the structure for the heat riser and the other in place of the barrel.

Let me know what you think

Louis

Louis Lines : O.K., You have made a decision to proceed with your R.M.H.s Build, I can tell you that you are on your way to a personal adventure you will long remember !

I am strongly recommending that you go to cobcottage.com to download your PDF Copy, $15.oo U.S. of Evan's and Jacksons' Great Book "Rocket Mass Heaters''
there is STILL No other book, in any language, with more 'Rocket Stove/Rocket Mass Heaters Family' Information ! This will allow you to understand WHY your R.M.H.s
internal plumbing should be made up from common 'soft red' brick and have a rectangular cross section of 30sq.'' to mate with 6'' stove pipe which will run horizontally
through your thermal mass!

You can take a look at Richsoil.com, a sister site to Permies.com and then click on Rocket Stoves, there you will find 12 videos that were either made by Professionals
or were made by people who were under the direction of a pro !

Too much of what is available in U-Tube land is Jreck, and should not be considered as helping you in an attempt to make a functioning rocket mass heater !

With a 6'' system you should easily flow the volume of air necessary to make a working R.M.H. that will flow horizontally (Not counting elbows )through 20' of thermal mass
with a Feed tube 10'' deep, a Burn tunnel 15'' and a Heat riser at least 30'' tall !

Do your research, make up a sketch of the idea of the tentative layout of your caravan And get back to us here, you will find that you have over 17,000 members here who
will be interested in your progress !

For the Good of The Craft ! Think like Fire, Flo like gas, Don't be the Marshmallow ! As always, your comments and questions are solicited and are Welcome ! Big Al

@Louis,

First of all, a 4" system is not easy to implement, very few do exist and running succesfully. Using a 4" stove pipe for the heart of the thing will lead to disappointment, when the thing is running as it should the pipe would hold out one month, tops. See a short but recent discussion on the same topic here.
Also, in a small two person's caravan there wouldn't be much room to implement a full scale bench system, I reckon.

And cooking on the top surface of the drum even in summer? I doubt that. Unless... you make the barrel interchangable for one which is shorter as the normal one, the minimum distance from riser end to top of the barrel, thus creating a really hot spot in the middle of the drum top. In addition, I've found out that when the stove is running healthy, throughout the innards there's a slight underpressure. This way, it would be possible to run it with small leaks during cooking. It proved possible to undo the bung hole at the top of a full running stove and film through the hole without the CO detector kicking into alarm. It would be sensible to buy a CO detector anyway.
I do agree with Allen at the points of using very dry and thin split wood and downloading the Rocket Mass Heater book by Ianto Evans and Leslie Jackson.

The exhaust pipe will come out at a low level. Leading it outside and up will automatically mean you have to insulate the whole of the outside stack. It would be better to lead the pipe straight up from the exhaust spot in single wall pipe and change to triple wall pipe under the ceiling and out.

A suggestion: look into the possibility of purchasing a ready-cast 4" core. That would take the difficult part of the job out of your hands, so you are free to concentrate on implementing a reasonable efficient heat conducting system around it. I am biased about this core, so when you decide to try it all by yourself, please do.

Just to say I moved from small caravan as described to a yurt as the heating in winter was so difficult and dangerous in the van and no question of coking in a hot summer on a hot stove in a tin can! I also lost a van to fire so please take great care. The Mongolian stove in the yurt is fabulous in winter and very simple in design. But I do not cook on that in summer either.

Peter Berg wrote:@Louis,

First of all, a 4" system is not easy to implement, very few do exist and running succesfully. Using a 4" stove pipe for the heart of the thing will lead to disappointment, when the thing is running as it should the pipe would hold out one month, tops. See a short but recent discussion on the same topic here.
Also, in a small two person's caravan there wouldn't be much room to implement a full scale bench system, I reckon.

And cooking on the top surface of the drum even in summer? I doubt that. Unless... you make the barrel interchangable for one which is shorter as the normal one, the minimum distance from riser end to top of the barrel, thus creating a really hot spot in the middle of the drum top. In addition, I've found out that when the stove is running healthy, throughout the innards there's a slight underpressure. This way, it would be possible to run it with small leaks during cooking. It proved possible to undo the bung hole at the top of a full running stove and film through the hole without the CO detector kicking into alarm. It would be sensible to buy a CO detector anyway.
I do agree with Allen at the points of using very dry and thin split wood and downloading the Rocket Mass Heater book by Ianto Evans and Leslie Jackson.

The exhaust pipe will come out at a low level. Leading it outside and up will automatically mean you have to insulate the whole of the outside stack. It would be better to lead the pipe straight up from the exhaust spot in single wall pipe and change to triple wall pipe under the ceiling and out.

A suggestion: look into the possibility of purchasing a ready-cast 4" core. That would take the difficult part of the job out of your hands, so you are free to concentrate on implementing a reasonable efficient heat conducting system around it. I am biased about this core, so when you decide to try it all by yourself, please do.